Windshield heater



June 25, 1935.

M1. ZAIGER LWLUDSIIIELD HEATER Filed Jan. 26, 1935 e Non Hrw Mw Z@Patented June 25, 1935 luru'rlao STATESv PATENT OFFIcE 3 Claims.

This invention relates to electric windshield heaters of the so-calledglass pane type and the object of the invention is to provide a.Windshield heater of this construction with a thermostat element tocontrol the supply of current to the heating element, the constructionbeing such that when the temperature in the chamber formed by thewindshield heater and the windshield reaches a predetermined point thecircuit supplying the electric heating units will be automaticallyopened.

One advantage of this construction is that whenever there is suliicientheat in said chamber to enable the windshield heater to perform properlyits functions, the supply of further current to the coils willautomatically cease, thereby preventing any unnecessary drain on thebattery. A further advantageis that when the temperature in saidchamber' falls below that point at which the windshield heater willfunction properly, the circuit for the heating coils will beautomatically closed thereby supplying current to said coils.

A further advantage is that by thus controlling the current which issupplied to the heating coils, all danger that the coils will developsuilcient heat to crack the windshield glass is avoided.

In order to give an understanding of my invention I have illustrated inthe drawing a selected embodiment thereof which will now be describedafter which the novel features will be pointed out in the appendedclaims.

In the drawing:

Fig. 1 is a view of a windshield heater embodying my invention with aportion broken out, said iigure showing the side ofthe windshield heaterwhich is applied to the Windshield.

Fig. 2 is an enlarged section on the line 2--2 Fig. 1.

Fig. 3 is an enlarged section on the line 3-3 Fig. 1.

In the drawing, l indicates the windshield of the automobile and 2indicates generally the windshield heater. This heater is of the typecomprising a skeleton frame element 3 supporting a glass pane Il andhaving located within it electrical heating coils 5. The frame elementis formed with the exterior metal frame member 6 and with a rubberglass-holding member 'I which ts within the exterior frame 6 and isformed with the flexible lip 8 adapted to engage the windshield I. Thisrubber glass-holding member 1 is formed with a glass-receiving groove 9in which the edges of the glass pane 4 are received as shown best inFig. 2. The exterior frame member i is formed with extensions I0 whichcarry suction cups II by which the heater is secured to the windshield.

The heating coils 5 which extend from one end to the other of the heaterare secured at one end 5 to a strip I2 situated inside of theglass-holding member 1 and insulatedfrom the metal frame member i, andat the other end said coils are secured to the ends of another strip I 3also situated inside of the glass-holding member 1 but electril0 callyconnected to the exterior frame member 6.

As herein shown the strip I3 is retained in place by two bolts I4 whichextend from said strip, through the glass-holding member 1 and throughthe side flange ofthe frame member 6.

A similar bolt I5 may be used for retaining the insulated strip I2 inplace, said bolt I5 being insulated irom the outer frame member 6 bysuitable 4insulation I6. i

I'l and Il indicate two terminals through which 20 .the current issupplied to the coils 5, these terminals being of a construction topermit them to be connected to a supply circuit through the medium of anordinary plug connection. The terminal Il may be secured directly to theouter 25 frame member 5. The terminal I1 is insulated from the outerframe member 6 and is connected to the strip I2 through the medium of athermostatic element. This thermostatic element is indicatedv at I 9 andis in the form of a strip of bi- 30 metallic material such as is usuallyused in thermostats, one end of which is electrically connected to theterminal I1. The terminal I1 is shown as having a shank portion 20 whichextends through the frame member 6, the rubber 36 glass-holding member1, and the strip I2, the end of said shank passing through thethermostatic element I9 and having a nut 2| screw-threaded thereto forretaining the thermostatic element I! in place. The terminal I1 isinsulated from both 40 the outer frame member` 6 and the strip I2 bysuitable insulation 22.

The outer or free end of the thermostatic element I9 carries a contact23 adapted to co-operate with a contact 2l adiustably carried by the 45strip I2. 'I'his contact 24 has a screw-threaded stem 25 which extendsthrough the strip I2 and is held in position by two lock nuts 26, 21screwsthreaded to the stem and engaging opposite faces of the strip I2.The outer end ofthe stem 25 is 50 provided with a screw driver notch 28and the glass-holding member 'l as well as the outer frame member i iscut away as at 29 to provide an opening to receive the outer end of thestem. By adjusting the nuts 2s, 21 the Contact 24 may be 55 adjusted tocause the circuit to open at any desired temperature.

The thermostatic element I9 is so constructed that as the temperaturedecreases it tends to flex or bend toward the left Fig. 1 and when thetemperature rises it tends to ex or bent toward the right. When theheater is in use the heating circuit includes the terminal I'I, the.thermostatic element I9, contacts 23, 24, strip I2, heating coils 5,strip I3, frame element 6 and the terminal I8.

The thermostat will be so adjusted that when the temperature is in thevicinity of a freezing temperature, the thermostatic element I9 willassume a position in which a contact 23 is closed onto the contact 24,thereby closing the heating circuit. The heat developed from the heatingcoils 5 will heat the air in the chamber 30 between the glass pane 4 andwindshield I, and as the temperature rises in said chamber 30 thethermostatic element tends to move toward the right Fig. 1. When apredetermined temperature has been reached the thermostatic element willassume a position in which the contacts 23, 24 are separated therebybreaking the heating circuit. This circuit will remain broken at thethermostatic contacts until the temperature in the chamber 30 againfalls below the predetermined point, at which time the circuit will beautomatically closed.

With this invention, therefore, when the windshield heater is in use thecurrentgwill be supplied to the heating. coils only when the temperaturein the chamber 30 is below a predetermined point and the current will becut off automatically as soon as this predetermined temperature has beenreached in the chamber 30. With this device, therefore, current will besupplied to the heating coils only when needed to maintain the requiredtemperature in the chamber 39, thereby avoiding unnecessary drain on thebattery of the automobile and also avoiding the possibility that thewindshield will become heated suilciently to cause it to crack.

While I have shown one embodiment of the invention, I do not wish tobevlimited to the cons tructional features illustrated.

3| indicates. a casing or housing which is secured to the strip I2 and.which encloses the thermostatic element I9. 'I'his housing may be madeof perforated material so as to allow theefree circulation of airtherethrough. 'Ihe housing is shown as having ears 32 by which it issecured to the strip I2 through the medium of suitable screws.

I claim:

1. A windshield heater comprising a frame element including an exteriormetal frame member and a glass-holding member of rubber carried thereby,said glass-holding member having a exible lip to engage the windshieldand a. glasssupporting groove, a pane of glass having its edges receivedin said groove, two resistor-supporting strips at opposite ends of theframe both situated within the glass-supporting member,

one of whichis insulated from the metal frame member and the other ofwhich is electrically connected thereto, heating resistors connected atone end to one strip and at the other end to the other strip, a supplyterminal insulated from the metal frame member, a thermostatic elementconnected to said terminal and a contact carried by the insulatedresistor-supporting strip and cooperating with the thermostatic elementto close the heating circuit when the temperature is belaw apredeterminedpoint and to open said circuit when the temperature isabove said point.

2. A windshield heater comprising a frame element including an exteriormetal frame member and a glass-supporting member of rubber fittingwithin the frame member, said glass-supporting member having a flexiblelip to engage the windshield, two resistor-supporting, strips situatedwithin the glass-supporting member, one at each end of the frame, onestrip being insulated from the metal frame member and the other stripbeing electrically connected thereto, heating resistors within the frameconnected at one end to one strip and at the other end to another strip,two circuit terminals, one of which is connected to the metal framemember, the other terminal having a shank extending through the metalframe member, the glass-supporting member and the insulated strip andbeing insulated from both said strip and thepframe member, athermostatic element connected to said terminal member, a contactadjustably carried by the insulated strip and with which thethermostatic element co-operates to close the heating circuit when thetemperature is below a predetermined point and to open said circuit whenthe temperature is above said point, said metal frame member andglass-supporting member being cut away to give access to the stem ofsaid contact from the exterior of the frame for adjustment purposes.

3. A windshield heater comprising a frame element having a exible lip toengage a windshield, a glasspane carried by said frame element andforming with the windshield a heating chamber, two resistor-supportingstrips at opposite ends of the frame on the interior thereof, one ofwhich strips is insulated from the metal frame member and the other ofwhich is electrically connected thereto, heating resistors connected atone end to one strip and at the other end to the other strip, twocircuit terminals carried by the metal frame member, one of theterminals beingI insulated therefrom, a thermostatic element mountedwithin said frame member and connected to said latter terminal and acontact carried by the insulated resistor-supporting strip andco-operating with the thermostatic element to close the heating circuitwhen the temperature within said chamber is below a predetermined pointand to open said circuit when the temperature rises above said point.

MAX ZAIGER.

